Photo taken by the Hubble Space Telescope, shows a snapshot of when the universe was just a toddler, 600 million years after the Big Bang, the earliest image yet. AP Photo/NASA.

By: Seth Borenstein, AP Science Writer

WASHINGTON, DC (AP).-The Hubble Space Telescope has captured the earliest image yet of the universe  just 600 million years after the Big Bang, when the universe was just a toddler.

Scientists released the photo Tuesday at a meeting of the American Astronomical Society. It's the most complete picture of the early universe so far, showing galaxies with stars that are already hundreds of millions of years old, along with the unmistakable primordial signs of the first cluster of stars.

These young galaxies haven't yet formed their familiar spiral or elliptical shapes and are much smaller and quite blue in color. That's mostly because at this stage, they don't contain many heavy metals, said Garth Illingworth, a University of California, Santa Cruz, astronomy professor who was among those releasing the photo.

"We're seeing very small galaxies that are seeds of the great galaxies today," Illingworth said in a news conference.

Until NASA's Hubble telescope was repaired and upgraded last year, the farthest back in time that astronomers could see was about 900 million years after the Big Bang, Illingworth said. Hubble has been key in helping determine the age of the universe at about 13.7 billion years, ending a long scientific debate about a decade ago.

As far back as Hubble can see, it still doesn't see the first galaxies. For that, NASA will have to rely on a new observatory, the $4.5 billion James Webb telescope, which is set to launch in about four years.

"We are on the way to the beginning," said astrophysicist Neil deGrasse Tyson of the American Museum of Natural History. "Every step closer to the beginning tells you something you did not know before."

The new Hubble picture captures those distant simpler galaxies juxtaposed amid closer, newer and more evolved ones. The result is a cosmic family photo that portrays galaxies at different ages and stages of development over the course of more than 13 billion years.

Tyson, who was not involved in the Hubble image research, said most people only like their own baby pictures, but Hubble's photo is different: "These are the baby pictures for us all, hence the widespread interest."